between adjacent scan lines in an otherwise uniform pattern. microprinting is an anti - counterfeiting technique in which very small text is added to the artwork. a 2d barcode that is used for adding web links or other types of information to a printed page or a web page. the technology is somewhat similar to qr codes. the area between highlight and shadow area of a subject ’ s face in halftone image. colors or graylevels of intermediate value ( the range from 25 % to 75 % value ). ‘ magnetic ’ ink, ink with iron particles that can be magnetized, used for check printing. - abbreviation for management of information services – the designation for the field of computer solutions internal to an organization. - abbreviation for management information system - a computer application or set of applications used for managing processing processes, such as costing, stock control or production control. abbreviation for multipurpose internet mail extensions – mime is a standard that allows the embedding of arbitrary documents and other binary data of known types ( images, sound, video, and so on ) into e - mail handled by ordinary internet electronic mail interchange protocols. type of web press that is used to print brochures, newsletters, and other products whose flat trim size is typically 11 by 17 inch. mini webs use rolls that are 11 to 14 inches wide. synonym for lowercase or for a lowercase letter. symbolic names or letter combinations that permit that one set of codes to represent a more complex, longer set or string of codes. a repetitive interference pattern. in printing, it can be caused by interference between the dot patterns of the different colors or by interference between a pattern in the data being printed and the screened dots. in scanning, moire can be caused by interference between the grid of the scanner ccds and patterns in the original that is being scanned. a cotton fabric used on the dampening rollers of a printing press. an ink pigment made from precipitating lead molybdate, lead sulfate and lead chromate. having or being of one color. having a single wavelength. laser beams have a narrow frequency range that is very nearly monochromatic. letterspacing that is the same for all characters regardless of their shape or width. courier is an example of a monospaced font. a single image made up of photographs or drawings. sound that the dogcow makes spotty or uneven ink absorption. abbreviation for motion pictures experts group : data compression standard for motion - video and audio coarse muslin glue


mar. 19, 1998 west lafayette, ind. - - purdue university researchers have developed a new class of materials that has a wide variety of potential applications, from a coating to repel liquids to a membrane that could be used in wastewater treatment and drug delivery. the materials are called co - polymer networks, which are " built " from intersecting chains of small molecules linked together to form a larger, mesh - like structure. the two molecular " building blocks, " or monomers, used in the new materials are acrylic acid and a derivative of oligoethylene glycol. the properties of an individual material in the class can be varied depending on the relative amounts of the monomers used to prepare it. " because these materials are co - polymers, we can control their properties more precisely and over a wider range than we could if they were made of a single type of monomer, " says robert scott, a ph. d. candidate at purdue who helped develop the material. " this level of versatility and control allows for a number of applications. " the new class of materials is unique in that it is the first time materials with such a wide variety of properties have been derived from a combination of these two monomers, says scott ' s adviser nicholas peppas, the showalter distinguished professor at purdue. peppas has conducted research in polymers for more than 26 years and has developed new materials and polymers for applications that include biomedical applications. " the most exciting thing about this research is that we ' ve not only developed a class of materials with diverse properties, but we ' ve also come to understand fundamentally, on a molecular level, the basis for those properties, " scott says. scott will present information on the new materials in two talks march 16 at the annual meeting of the american physical society in los angeles. his research has been funded by the national science foundation and the national institutes of health. the new materials, which were developed over the past four years with the help of lab assistant atsmon shahar, are particularly suited for separations applications, such as filtering mechanisms used in wastewater treatment, where only certain substances are allowed to pass through the mesh created by the interlacing polymers. " as we increase the acrylic acid content of the materials, the oligoethylene glycol chains that make up the network move further apart, increasing the mesh size, which in turn determines what substances can pass through, " scott explains. " by varying the acrylic acid content, as well as other


apr. 17, 2012 researchers from the complutense university of madrid ( ucm, spain ) have mathematically shown that particles charged in a magnetic field can escape into infinity without ever stopping. one of the conditions is that the field is generated by current loops situated on the same plane. at the moment this is a theoretical mathematical study, but two researchers from ucm have recently proved that, in certain conditions, magnetic fields can send particles to infinity, according to the study published in the journal quarterly of applied mathematics. " if a particle ' escapes ' to infinity it means two things : that it will never stop, and " something else, " antonio diaz - cano, one of the authors, explained. regarding the first, the particle can never stop, but it can be trapped, doing circles forever around a point, never leaving an enclosed space. however, the " something else " goes beyond the established limits. " if we imagine a spherical surface with a large radius, the particle will cross the surface going away from it, however big the radius may be " the researcher declares. scientists have confirmed through equations that some particles can escape infinity. one condition is that the charges move below the activity of a magnetic field created by current loops on the same plane. other requirements should also be met : the particle should be on some point on this plane, with its initial speed being parallel to it and far away enough from the loops. " we are not saying that these are the only conditions to escape infinity, there could be others, but in this case, we have confirmed that the phenomenon occurs, " diaz - cano states. " we would have liked to have been able to try something more general, but the equations are a lot more complex. " in any case, the researchers recognise that the ideal conditions for this study are " with a magnetic field and nothing else. " reality always has other variables to be considered, such as friction and there is a distant possibility of going towards infinity. nonetheless, the movement of particles in magnetic fields is a " very significant " problem in fields such as applied and plasma physics. for example, one of the challenges that the scientists that study nuclear energy face is the confinement of particles to magnetic fields. accelerators such as large hadron collider ( lhc ) of the european organisation for nuclear research ( cern ) also used magnetic fields to accelerate particles. in these conditions they do not escape to infinity, but they remain doing circles until they acquire the speed that the experiments need. other social book


nov. 19, 2012 sound waves are commonly used in applications ranging from ultrasound imaging to hyperthermia therapy, in which high temperatures are induced, for example, in tumors to destroy them. in 2010, researchers at caltech led by chiara daraio, a professor of aeronautics and applied physics, developed a nonlinear acoustic lens that can focus high - amplitude pressure pulses into compact " sound bullets. " in that initial work, the scientists demonstrated how sound bullets form in solids. now, they have done themselves one better, creating a device that can form and control those bullets in water. the nonlinear acoustic lens is constructed from chains strung with stainless - steel spheres that are oriented parallel to one another - - and squeezed together - - to form an array. the gadget was inspired by newton ' s cradle, a popular toy that consists of a line of identical balls suspended by wires from a frame. when an end ball is pulled back and released, it slams into the next ball, causing the last ball in the line to fly outward. similarly, in the acoustic lens, striking one end of the array generates compact nonlinear pulses of sound - - solitary waves that propagate through the lens and can be tightly focused on a target area ; when they coalesce at this focal point, they produce a significantly amplified version : the sound bullet. these intense pressure waves may be used to obliterate tumors or kidney stones - - leaving surrounding tissues unharmed - - or probe objects like ship hulls or bridges for unseen defects. in the new work, the lens has been made more accurate, and a waterproof interface, which efficiently transmitted the pulses, was inserted between the chains and water. " we use water as a target medium with the idea that the acoustic lens could be used for underwater imaging and / or biomedical applications, " says postdoc carly donahue, who helped refine the device. " currently, our work is fundamental in nature. we are focused on demonstrating proof of principle and establishing the technical strengths and weaknesses, which will inform the future design of engineering devices for specific applications, " she adds. " for example, using these systems in biomedical applications requires reducing their dimensions and learning about the related scaling effects. creating commercially viable devices will require the involvement of industrial partners. " donahue discusses the technology and its potential applications in a talk at the aps division of fluid dynamics meeting, which will take place november 18 - 20, 2012 at the san diego convention center, located near the historic gaslamp district on the waterfront, in san


last week ' s announcement of the discovery of a new particle seemed to answer one of the great outstanding questions in physics. but for those who haven ' t been immersed in all things lhc, the results were likely to raise all sorts of new questions ( along with " what was all the fuss about again? " ). so, to help navigate the post - higgs world, we put together a short q & a, based on questions that some of the ars staff had. i know we detected it in the large hadron collider, but how did they actually make higgs bosons? there are two ways to answer that question. the first is that we ' re simply converting energy into matter. the protons in the collider carry a tremendous amount of energy, and it has to go somewhere. given einstein ' s e = mc2, we know that some of that energy can be converted into matter. that ' s why things that are much heavier than two protons at rest can pop out of the collisions. but einstein ' s equations aren ' t magic, in that particles don ' t just poof into existence — there are actual processes that create them. in the lhc, the most common process that ends in a higgs boson is gluon fusion. gluons are the ( apparently massless ) carriers of the strong force that holds quarks together to form things like protons and neutrons. if two of them merge, then one possible outcome is a single higgs particle. everyone says that this particle was predicted by the standard model, but how exactly? what was missing that made people theorize the higgs? the standard model describes the properties of fundamental particles and the forces that mediate their interactions. some of these, like the photon, are massless ; others, like the w and z bosons that mediate the weak force, weigh as much as entire atoms ( including some that the weak force causes to decay ). although its possible to just say " this is what these things weigh, " physicists find this sort of approach dissatisfying. so, they developed a theoretical mechanism that could supply some particles with mass. several papers, appearing about the same time, suggested that there ' s a pervasive field that all particles can interact with. some, like the photon, don ' t, and remain massless. others, like the w and z bosons, undergo large interactions with the field, picking up a large mass in the process.


the theory. and there ' s a major extension to the standard model, called supersymmetry, that suggests that the standard model ' s particles are all parts of larger families, meaning that there would be multiple higgs bosons, and we ' ve only found one. matt strassler told ars that a few more exotic theories suggest there will be higgs - like particles that do very different things, some involving extra dimensions. it ' s only by making more of these bosons that we can start to tell these possibilities apart. which brings us to our next question. the key thing here is that, if we haven ' t found the standard model higgs, then we don ' t get to keep the standard model as it is. we could end up with a mildly tweaked version, we could have a standard model plus extensions, or we could be seeing hints of something much more significant. until we have a better understanding of the particle we ' re seeing, we can ' t tell any of these apart. if the large hadron collider was made to find the higgs, what ' s it going to do now? make more higgs, so we can answer the previous question, for starters. cern ' s director announced that it will run for a few extra months specifically to get a better statistical handle on whether this is the standard model higgs. beyond that, many other theoretical particles, including some of those predicted by things like supersymmetry, are already within reach of the energies at the lhc. once it restarts in a couple of years, it will be running at much higher energies, opening up a greater range for discovery. even if you don ' t think it ' s worth chasing down theoretical particles, the universe keeps telling us that dark matter is likely to be comprised of a heavy fundamental particle. the lhc should be able to spot these if they ' re really out there. does this eliminate the need to build another collider? actually, it will certainly inform, and possibly motivate, the construction of anything that comes next. the lhc may have been a great higgs discovery machine, but it ' s actually not so hot if we want to look at the higgs in detail ( and wanting the answers to the above should suggest we do ). the problem is that proton collisions are messy, since you ' re actually colliding what ' s essentially a bag of quarks, gluons, and virtual particles, all of which


a new kind of neutrino transformation esnet helps scientists discover how neutrinos flavor - shift march 8, 2012 neutrinos, the wispy particles that flooded the universe in the earliest moments after the big bang, are continually produced in the hearts of stars and other nuclear reactions. untouched by electromagnetism, they respond only to the weak nuclear force and even weaker gravity, passing mostly unhindered through everything from planets to people. years ago scientists also discovered another hidden talent of neutrinos. although they come in three basic “ flavors ” — electron, muon and tau — neutrinos and their corresponding antineutrinos can transform from one flavor to another while they are traveling close to the speed of light. how they do this has been a long - standing mystery. but some new, and unprecedentedly precise, measurements from the multinational daya bay neutrino experiment are revealing how electron antineutrinos “ oscillate ” into different flavors as they travel. this new finding from daya bay opens a gateway to a new understanding of fundamental physics and may eventually solve the riddle of why there is far more ordinary matter than antimatter in the universe today. the international collaboration of researchers is made possible by advanced networking and computing facilities. in the u. s., the department of energy ’ s high - speed science network, esnet, speeds data to the national energy research scientific computing center ( nersc ) where it is analyzed, stored and made available to researchers via the web. both facilities are located at the doe ’ s lawrence berkeley national laboratory ( berkeley lab ). nuclear reactors of the china guangdong nuclear power group at daya bay and nearby ling ao produce millions of quadrillions of elusive electron antineutrinos every second. the six massive detectors buried in the mountains adjacent to the powerful reactors, make up the daya bay experiment. researchers in the collaboration count the number of electron antineutrinos detected in the halls nearest the daya bay and ling ao reactors and calculate how many would reach the detectors in the far hall if there were no oscillation. the number that apparently vanishes on the way ( oscillating into other flavors, in fact ) gives the value of theta one - three, written θ13. shortly after experimental data is collected, it travels across the pacific ocean via the national science foundation ’ s gloriad network, which connects to esnet backbone in seattle, washington. from seattle, esnet carries


author ( s ) : a. m. waked nanotechnology is considered to be the most important theoretical and applicative framework of human knowledge in the near future, breakthroughs are restricted to few applications. one is being the conservation and restoration of for the architecture profession nanotechnology will be able to change the way we build, and will greatly impact construction materials and their properties as well. however, materials will behave in many different ways as we are able to more precisely control their properties at nano - composites, which combine new nano - materials with more traditional ones and can be many times stronger than standard materials, and will dramatically improve the performance, durability, and strength to weight ratio of these materials. as materials gain such transient features architectural design and construction will evolve by transforming the essential properties of matter. this study of material is considered an emerging field, so this paper will retry to represent the most recent applications of nano materials of the conservation of nanotechnology, nano - materials, conservation. size : 1, 681 kb paper doi : 10. 2495 / str110481 the full article you can purchase the full text version of this article in adobe pdf format for the above price. please click the ' buy paper ' icon below to purchase this paper. this page to a colleague. this paper can be found in the following bookstructural studies, repairs and maintenance of heritage architecture xiibuy


researchers at the research center quantop at the niels bohr institute at the university of copenhagen ( denmark ) have constructed an atomic magnetometer, which has achieved the highest sensitivity allowed by quantum mechanics. sensitive magnetometers could be used to measure electrical activity in the human brain and heart. the results have been published in physical review letters. the ultimate sensitivity of any measurement is determined by the laws of quantum mechanics. these laws, normally most noticeable at the atomic level, become relevant for larger objects as the sensitivity of measurements increase with the development of new technologies. atoms as magnetic sensors atoms have a fundamental property called spin, which makes the atoms act like small magnets that are sensitive to external magnetic fields and can be used as magnetic sensors. but each of the atomic spins has a quantum uncertainty, which sets the fundamental limit on the smallest external magnetic fields that the atom can sense. conventional atomic magnetometers are usually built with a very large number of atoms, because the overall sensitivity of billions of atoms is much greater than that of a single atom. but on the other hand, it is much more difficult to reach the limit of sensitivity given by quantum mechanics. however, researchers at the quantop center have constructed an atomic magnetometer with the ultimate sensitivity allowed by quantum mechanics. “ moving towards the goal we had to ensure that our method made it possible to suppress not only sources of technical errors, such as fluctuations in the magnetic field due to public transportation, radio waves and so on, but also to eliminate a number of errors of pure quantum mechanical origin ”, explains professor eugene polzik, director of the quantop center at the niels bohr institute. from brains to explosives as a result, the magnetometer can measure in a second a field, which is a hundred billion times weaker than the earth ’ s magnetic field. the magnetometer has a wide range of possible uses, because where there is an electric current, there is also a magnetic field. measurements of magnetic fields can reveal information about the electrical activity in the human brain and heart, the chemical identity of certain atoms, for example, explosives, or simply indicate the presence or absence of metal. the new quantum magnetometer functions at room temperature, which makes it a good alternative to the expensive commercial superconducting magnetometers ( the so - called ‘ squids ’ ). “ our quantum magnetometer functions at room temperature which makes it a good alternative to the expensive commercial superconducting magnometers ( the so - called ‘ squids ’ ). it has the


joint dark energy mission program ( s ) : physics of the cosmos take all the stars, all the planets and everything we can see and detect with telescopes and add them all up. that total will represent only four percent of the universe. if the universe came with a list of ingredients, the ordinary atoms that make up stars, trees and animals would be at the bottom of the label, like some exotic spice. nearly 25 percent of the universe takes the form of dark matter, a mysterious substance that seems to be intrinsically different from ordinary atoms. and the rest, a whopping 70 percent of the universe, is a mysterious quantity we call dark energy. as a comparison, remember that about 70 percent of the earth ' s surface is covered with water. imagine not knowing what water is! that ' s the situation we ' re in with dark energy. the observations that first led to this confusing situation were the observations of the velocities of distant supernovae. the key is that, as we look at supernovae far away, we are seeing them as they were long ago. the fact that they were moving away from us more slowly than expected showed that the expansion of the universe, instead of slowing due to gravity, was actually accelerating. no known component of the universe could have caused this acceleration. suggestions for unknown components have included a new kind of fluid, called " quintessence, " an unexpected property of the vacuum of empty space, or a fundamental modification of einstein ' s theory of gravity. whatever the final explanation may be, it will revolutionize our understanding of the physics of the universe. the national academy of sciences has stated that the nature of dark energy is probably the most important question in astronomy today. it has been called the deepest mystery in physics, and its resolution is likely to greatly advance our understanding of matter, space, and time. in response to recommendations by the national academy of sciences, nasa and the doe spent several years working together to evaluate a possible future mission which would study the expansion history of the universe. however, a result of the 2010 decadal report was that jdem was not selected as one of the ranked recommendations. the new wfirst observatory was instead recommended to settle the essential questions in both dark energy and exoplanet research. last updated : june 6, 2012


key : " s : " = show synset ( semantic ) relations, " w : " = show word ( lexical ) relations display options for sense : ( gloss ) " an example sentence " - s : ( n ) approach, attack, plan of attack ( ideas or actions intended to deal with a problem or situation ) " his approach to every problem is to draw up a list of pros and cons " ; " an attack on inflation " ; " his plan of attack was misguided " - s : ( n ) approach, approaching, coming ( the act of drawing spatially closer to something ) " the hunter ' s approach scattered the geese " - s : ( n ) access, approach ( a way of entering or leaving ) " he took a wrong turn on the access to the bridge " - s : ( n ) approach path, approach, glide path, glide slope ( the final path followed by an aircraft as it is landing ) - s : ( n ) approach, approaching ( the event of one object coming closer to another ) - s : ( n ) overture, advance, approach, feeler ( a tentative suggestion designed to elicit the reactions of others ) " she rejected his advances " - s : ( n ) approach, approaching, coming ( the temporal property of becoming nearer in time ) " the approach of winter " - s : ( n ) approach ( a close approximation ) " the nearest approach to genius " - s : ( n ) approach, approach shot ( a relatively short golf shot intended to put the ball onto the putting green ) " he lost the hole when his approach rolled over the green " - s : ( v ) approach, near, come on, go up, draw near, draw close, come near ( move towards ) " we were approaching our destination " ; " they are drawing near " ; " the enemy army came nearer and nearer " - s : ( v ) border on, approach ( come near or verge on, resemble, come nearer in quality, or character ) " this borders on discrimination! " ; " his playing approaches that of horowitz " - s : ( v ) set about, go about, approach ( begin to deal with ) " approach a task " ; " go about a difficult problem " ; " approach a new project " - s : ( v ) approach, come near ( come near in time ) " winter is approaching " ; " approaching old age " - s : ( v ) approach ( make advances to someone, usually with a proposal


key : " s : " = show synset ( semantic ) relations, " w : " = show word ( lexical ) relations display options for sense : ( gloss ) " an example sentence " - s : ( n ) scale, scale of measurement, graduated table, ordered series ( an ordered reference standard ) " judging on a scale of 1 to 10 " - s : ( n ) scale ( relative magnitude ) " they entertained on a grand scale " - s : ( n ) scale ( the ratio between the size of something and a representation of it ) " the scale of the map " ; " the scale of the model " - s : ( n ) scale, scale leaf ( a specialized leaf or bract that protects a bud or catkin ) - s : ( n ) scale, scurf, exfoliation ( a thin flake of dead epidermis shed from the surface of the skin ) - s : ( n ) scale, musical scale ( ( music ) a series of notes differing in pitch according to a specific scheme ( usually within an octave ) ) - s : ( n ) scale, weighing machine ( a measuring instrument for weighing ; shows amount of mass ) - s : ( n ) scale ( an indicator having a graduated sequence of marks ) - s : ( n ) plate, scale, shell ( a metal sheathing of uniform thickness ( such as the shield attached to an artillery piece to protect the gunners ) ) - s : ( n ) scale ( a flattened rigid plate forming part of the body covering of many animals ) - s : ( v ) scale ( measure by or as if by a scale ) " this bike scales only 25 pounds " - s : ( v ) scale ( pattern, make, regulate, set, measure, or estimate according to some rate or standard ) - s : ( v ) scale ( take by attacking with scaling ladders ) " the troops scaled the walls of the fort " - s : ( v ) scale, surmount ( reach the highest point of ) " we scaled the mont blanc " - s : ( v ) scale ( climb up by means of a ladder ) - s : ( v ) scale, descale ( remove the scales from ) " scale fish " - s : ( v ) scale ( measure with or as if with scales ) " scale the gold " - s : ( v ) scale ( size or measure according to a scale ) " this model must be scaled down "


in quantum mechanics quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle - like and wave - like behavior and interactions of energy and matter. it departs from classical mechanics primarily at the atomic and subatomic..., the particle in a box model ( also known as the infinite potential well or the infinite square well ) describes a particle free to move in a small space surrounded by impenetrable barriers. the model is mainly used as a hypothetical example to illustrate the differences between classical what " classical physics " refers to depends on the context. when discussing special relativity, it refers to the newtonian physics which preceded relativity, i. e. the branches of physics based on principles developed before the rise of relativity and quantum mechanics... and quantum systems. in classical systems, for example a ball trapped inside a heavy box, the particle can move at any speed within the box and it is no more likely to be found at one position than another. however, when the well becomes very narrow ( on the scale of a few nanometers ), quantum effects become important. the particle may only occupy certain positive energy levels. likewise, it can never have zero energy, meaning that the particle can never " sit still ". additionally, it is more likely to be found at certain positions than at others, depending on its energy level. the particle may never be detected at certain positions, known as spatial nodes. the particle in a box model provides one of the very few problems in quantum mechanics which can be solved analytically, without approximations. this means that the observable properties of the particle ( such as its energy and position ) are related to the mass of the particle and the width of the well by simple mathematical expressions. due to its simplicity, the model allows insight into quantum effects without the need for complicated mathematics. it is one of the first quantum mechanics problems taught in undergraduate physics courses, and it is commonly used as an approximation for more complicated quantum systems. see also : the history of quantum mechanics the history of quantum mechanics, as it interlaces with the history of quantum chemistry, began essentially with a number of different scientific discoveries : the 1838 discovery of cathode rays by michael faraday ; the 1859 - 1860 winter statement of the black body radiation problem by gustav... the simplest form of the particle in a box model considers a one - dimensional system. here, the particle may only move backwards and forwards along a straight line with


; the 1859 - 1860 winter statement of the black body radiation problem by gustav... the simplest form of the particle in a box model considers a one - dimensional system. here, the particle may only move backwards and forwards along a straight line with impenetrable barriers at either end. the walls of a one - dimensional box may be visualised as regions of space with an infinitely large potential energy in physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. the si unit of measure for energy and work is the joule.... conversely, the interior of the box has a constant, zero potential energy. this means that no forces act upon the particle inside the box and it can move freely in that region. however, infinitely large force in physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. in other words, a force is that which can cause an object with mass to change its velocity, i. e., to accelerate, or which can cause a flexible object to deform... s repel the particle if it touches the walls of the box, preventing it from escaping. the potential energy in this model is given as is the length of the box and is the position of the particle within the box. in quantum mechanics, the wavefunction not to be confused with the related concept of the wave equationa wave function or wavefunction is a probability amplitude in quantum mechanics describing the quantum state of a particle and how it behaves. typically, its values are complex numbers and, for a single particle, it is a function of... gives the most fundamental description of the behavior of a particle ; the measurable properties of the particle ( such as its position, momentum and energy ) may all be derived from the wavefunction. can be found by solving the schrodinger equation the schrodinger equation was formulated in 1926 by austrian physicist erwin schrodinger. used in physics, it is an equation that describes how the quantum state of a physical system changes in time.... for the system is the reduced planck constant, is the mass mass can be defined as a quantitive measure of the resistance an object has to change in its velocity. in physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent :...


can be defined as a quantitive measure of the resistance an object has to change in its velocity. in physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent :... of the particle, is the imaginary unit in mathematics, the imaginary unit allows the real number system ℝ to be extended to the complex number system, which in turn provides at least one root for every polynomial. the imaginary unit is denoted by,, or the greek... inside the box, no forces act upon the particle, which means that the part of the wavefunction inside the box oscillates through space and time with the same form as a free particle in physics, a free particle is a particle that, in some sense, is not bound. in classical physics, this means the particle is present in a " field - free " space. - classical free particle : the classical free particle is characterized simply by a fixed velocity... are arbitrary complex number a complex number is a number consisting of a real part and an imaginary part. complex numbers extend the idea of the one - dimensional number line to the two - dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part... s. the frequency of the oscillations through space and time are given by the wavenumber in the physical sciences, the wavenumber is a property of a wave, its spatial frequency, that is proportional to the reciprocal of the wavelength. it is also the magnitude of the wave vector... and the angular frequency in physics, angular frequency ω is a scalar measure of rotation rate. angular frequency is the magnitude of the vector quantity angular velocity... respectively. these are both related to the total energy of the particle by the expression which is known as the dispersion relation in physics and electrical engineering, dispersion most often refers to frequency - dependent effects in wave propagation. note, however, that there are several other uses of the word " dispersion " in the physical sciences.... for a free particle. the size ( or amplitude amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. for example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation... ) of the wavefunction at a given position


oscillating system. for example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation... ) of the wavefunction at a given position is related to the probability of finding a particle there by. the wavefunction must therefore vanish everywhere beyond the edges of the box. also, the amplitude of the wavefunction may not " jump " abruptly from one point to the next. these two conditions are only satisfied by wavefunctions with the form is a positive, whole number. the wavenumber is restricted to certain, specific values given by is the size of the box. negative values of are neglected, since they give wavefunctions identical to the positive solutions except for a physically unimportant sign change. finally, the unknown constant may be found by normalizing the wavefunction so that the total probability density of finding the particle in the system is 1. it follows that may be any complex number with absolute value in mathematics, the absolute value | a | of a real number a is the numerical value of a without regard to its sign. so, for example, the absolute value of 3 is 3, and the absolute value of - 3 is also 3... √ ( 2 / l ) ; these different values of a yield the same physical state, so a = √ ( 2 / l ) can be selected to simplify. the energies which correspond with each of the permitted wavenumbers may be written as the energy levels increase with, meaning that high energy levels are separated from each other by a greater amount than low energy levels are. the lowest possible energy for the particle ( its zero - point energy zero - point energy is the lowest possible energy that a quantum mechanical physical system may have ; it is the energy of its ground state. all quantum mechanical systems undergo fluctuations even in their ground state and have an associated zero - point energy, a consequence of their wave - like nature... ) is found in state 1, which is given by the particle, therefore, always has a positive energy. this contrasts with classical systems, where the particle can have zero energy by resting motionless at the bottom of the box. this can be explained in terms of the uncertainty principle in quantum mechanics, the heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known..., which states that the product


the uncertainty principle in quantum mechanics, the heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known..., which states that the product of the uncertainties in the position and momentum of a particle is limited by it can be shown that the uncertainty in the position of the particle is proportional to the width of the box. thus, the uncertainty in momentum is roughly inversely proportional to the width of the box. the kinetic energy of a particle is given by, and hence the minimum kinetic energy of the particle in a box is inversely proportional to the mass and the square of the well width, in qualitative agreement with the calculation above. in classical physics, the particle can be detected anywhere in the box with equal probability. in quantum mechanics, however, the probability density for finding a particle at a given position is derived from the wavefunction as for the particle in a box, the probability density for finding the particle at a given position depends upon its state, and is given by thus, for any value of n greater than one, there are regions within the box for which, indicating that spatial nodes exist at which the particle cannot be found. in quantum mechanics, the average, or expectation value of the position of a particle is given by for the steady state particle in a box, it can be shown that the average position is always, regardless of the state of the particle. for a superposition of states, the expectation value of the position will change based on the cross term which is proportional to if a particle is trapped in a two - dimensional box, it may freely move in the - directions, between barriers separated by lengths respectively. using a similar approach to that of the one - dimensional box, it can be shown that the wavefunctions and energies are given respectively by where the two - dimensional wavevector is given by for a three dimensional box, the solutions are where the three - dimensional wavevector is given by an interesting feature of the above solutions is that when two or more of the lengths are the same ( e. g. ), there are multiple wavefunctions corresponding to the same total energy. for example the wavefunction with has the same energy as the wavefunction with. this situation is called degeneracy in physics, two or more different quantum states are said to be degenerate if they are all at the same energy level. statistically this means that they are


same energy as the wavefunction with. this situation is called degeneracy in physics, two or more different quantum states are said to be degenerate if they are all at the same energy level. statistically this means that they are all equally probable of being filled, and in quantum mechanics it is represented mathematically by the hamiltonian for the system having more... and for the case where exactly two degenerate wavefunctions have the same energy that energy level is said to be doubly degenerate. degeneracy results from symmetry in the system. for the above case two of the lengths are equal so the system is symmetric with respect to a 90° rotation. because of its mathematical simplicity, the particle in a box model is used to find approximate solutions for more complex physical systems in which a particle is trapped in a narrow region of low electric potential in classical electromagnetism, the electric potential at a point within a defined space is equal to the electric potential energy at that location divided by the charge there... between two high potential barriers. these quantum well a quantum well is a potential well with only discrete energy values. one technology to create quantization is to confine particles, which were originally free to move in three dimensions, to two dimensions, forcing them to occupy a planar region... systems are particularly important in optoelectronics optoelectronics is the study and application of electronic devices that source, detect and control light, usually considered a sub - field of photonics. in this context, light often includes invisible forms of radiation such as gamma rays, x - rays, ultraviolet and infrared, in addition to visible light..., and are used in devices such as the quantum well laser a quantum well laser is a laser diode in which the active region of the device is so narrow that quantum confinement occurs. the wavelength of the light emitted by a quantum well laser is determined by the width of the active region rather than just the bandgap of the material from which it is..., the quantum well infrared photodetector a quantum well infrared photodetector, is an infrared photodetector made from semiconductor materials which contain one or more quantum wells. these can be integrated together with electronics and optics to make infrared cameras for thermography. a very common well material is gallium arsenide,... and the quantum - confined stark effect the quantum - confined stark effect describes the effect of


these can be integrated together with electronics and optics to make infrared cameras for thermography. a very common well material is gallium arsenide,... and the quantum - confined stark effect the quantum - confined stark effect describes the effect of an external electric field upon the light absorption spectrum or emission spectrum of a quantum well. in the absence of an external electric field, electrons and holes within the quantum well may only occupy states within a discrete set... the probability density does not go to zero at the nodes if relativistic effects are taken into account. - finite potential well the finite potential well is a concept from quantum mechanics. it is an extension of the infinite potential well, in which a particle is confined to a box, but one which has finite potential walls. unlike the infinite potential well, there is a probability associated with the particle being found... - delta function potential - gas in a box in quantum mechanics, the results of the quantum particle in a box can be used to look at the equilibrium situation for a quantum ideal gas in a box which is a box containing a large number of molecules which do not interact with each other except for instantaneous thermalizing collisions... - particle in a ring in quantum mechanics, the case of a particle in a one - dimensional ring is similar to the particle in a box. the schrodinger equation for a free particle which is restricted to a ring is... - particle in a spherically symmetric potential - quantum harmonic oscillator the quantum harmonic oscillator is the quantum - mechanical analog of the classical harmonic oscillator. because an arbitrary potential can be approximated as a harmonic potential at the vicinity of a stable equilibrium point, it is one of the most important model systems in quantum mechanics... - delta potential well ( qm ) the delta potential is a potential that gives rise to many interesting results in quantum mechanics. it consists of a time - independent schrodinger equation for a particle in a potential well defined by a dirac delta function in one dimension.... - semicircle potential well - configuration integral ( statistical mechanics )


bnl chemistry department | photo - and radiation chemistry | group members | leaf facility layout | | leaf system components | | features of leaf | | leaf publications | research highlights from leaf : ionic liquids : designer solvents for a cleaner world ( pdf ) storing energy in dendrimer trees : stabilizing charge separation in dendrimers ( pdf ) they bend before they break : fast scission of chemical bonds ( pdf ) the center for radiation chemistry research ( crcr ) exploits pulse radiolysis techniques to study chemical reactions ( and other phenomena ) by subjecting samples to pulses of high - energy electrons. the reactions are followed by various methods of time - resolved spectroscopy and other detection techniques. the crcr includes the new picosecond laser - electron accelerator facility ( leaf ), a 2 mev van de graaff, and a cobalt - 60 source. user access to crcr facilities is encouraged, either through collaboration with bnl staff or via the bnl center for functional nanomaterials ( cfn ) user program. please contact one of our principal investigators or the general facility address ( email @ example. com ) for more information. the design of the leaf accelerator is innovative : the electron pulse is produced by laser light impinging on a photocathode inside a resonant cavity, radio frequency ( rf ) gun about 30 cm long. the emitted electrons are accelerated to 9. 2 mev within the length of the gun by ~ 15 megawatt pulse of rf power from a slac - type 2. 856 ghz klystron. the laser pulse is synchronized with the rf power to produce the electron pulse near the peak field gradient ( about 1 mev / cm ). thus the pulse length and intensity are a function of the laser pulse properties, and electron pulse lengths as short as 5 picoseconds are attainable. rf photocathode electron guns of this type have been built at brookhaven ' s accelerator test facility and source development laboratory as well as at several other laboratories and universities, but almost all of these installations are dedicated to accelerator physics or free electron laser development. the bnl chemistry department ' s leaf accelerator was the first photocathode gun accelerator in the world to be dedicated to pulse radiolysis studies. today, there are seven other pulse radiolysis facilities similar to leaf operating or under construction around the world. the international symposium on ultrafast accelerators for pulse radiolysis was held at the bnl chemistry department in june, 2004, to discuss the state -


| | this article may be too technical for most readers to understand. ( may 2011 ) | properties of magnetic materials change with temperature. in physics and materials science, the curie temperature ( tc ), or curie point, is the temperature where a material ' s permanent magnetism changes to induced magnetism, or vice versa. the force of magnetism is determined by magnetic moments. the curie temperature is the critical point where intrinsic magnetic moments change directions. magnetic moments are permanent dipole moments within the atom which are made up from electrons angular momentum and spin. materials have different structures of intrinsic magnetic moments that depend on temperature. it is at a material ' s specific curie temperature where they change directions. permanent magnetism is from aligned magnetic moments and induced magnetism is disordered magnetic moments forced to align in a magnetic field. for example, the ordered magnetic moments ( ferromagnetic, figure 1 ) change and become disordered ( paramagnetic, figure 2 ) at the curie temperature, and vice versa. higher temperatures make magnets weaker as spontaneous magnetism only occurs below the curie temperature. magnetic susceptibility only occurs above the curie temperature and can be calculated from the curie - weiss law which is derived from curie ' s law. in analogy to ferromagnetic and paramagnetic materials, the curie temperature can also be used to describe the temperature where a material ' s spontaneous electric polarisation changes to induced electric polarisation, or vice versa. | material | | curie temperature ( k ) | | iron ( iii ) oxide ( fe2o3 ) | | 948 | | iron ( ii, iii ) oxide ( feofe2o3 ) | | 858 | magnetic moments electrons inside atoms contribute magnetic moments from their own angular momentum and from their orbital momentum around the nucleus. magnetic moments from the nucleus are insignificant in contrast to magnetic moments from electrons. thermal contribution will result in higher energy electrons causing disruption to their order and alignment between dipoles to be destroyed. ferromagnetic, paramagnetic, ferrimagnetic and antiferromagnetic materials have different structures of intrinsic magnetic moments. it is at a material ' s specific curie temperature where they change properties. the transition from antiferromagnetic to paramagnetic ( or vice versa ) occurs at the neel temperature which is analogous to curie temperature. | below tc | | above tc | ferromagnetism the magnetic moments in a


the transition from antiferromagnetic to paramagnetic ( or vice versa ) occurs at the neel temperature which is analogous to curie temperature. | below tc | | above tc | ferromagnetism the magnetic moments in a ferromagnetic material. the moments are ordered and of the same magnitude in the absence of an applied magnetic field. paramagnetism the magnetic moments in a paramagnetic material. the moments are disordered in the absence of an applied magnetic field and ordered in the presence of an applied magnetic field. ferrimagnetism the magnetic moments in a ferrimagnetic material. the moments are aligned oppositely and have different magnitudes due to being made up of two different ions. this is in the absence of an applied magnetic field. antiferromagnetism the magnetic moments in a antiferromagnetic material. the moments are aligned oppositely and have the same magnitudes. this is in the absence of an applied magnetic field. materials with magnetic moments that change properties at the curie temperature ferromagnetic, paramagnetic, ferrimagnetic and antiferromagntic structures are made up of intrinsic magnetic moments. if all electrons within the structure are paired these moments cancel out due to having opposite spins and angular momentums and thus even with an applied magnetic field will have different properties and no curie temperature. a material is paramagnetic only above its curie temperature. paramagnetic materials are non - magnetic when a magnetic field is absent and magnetic when a magnetic field is applied. when the magnetic field is absent the material has disordered magnetic moments ; that is, the atoms are unsymmetrical and not aligned. when the magnetic field is present the magnetic moments are temporarily realigned parallel to the applied field ; the atoms are symmetrical and aligned. the magnetic moment in the same direction is what causes an induced magnetic field. for paramagnetism this response to an applied magnetic field is positive and known as magnetic susceptibility. the magnetic susceptibility only applies above the curie temperature for disordered states. sources of paramagnetism ( materials which have curie temperatures ) ; - all atoms which have unpaired electrons ; - atoms where inner shells are incomplete in electrons ; - free radicals ; above the curie temperature the atoms are excited, the spin orientation becomes randomised, but can be realigned in an applied field and the material paramagnetic. below


- atoms where inner shells are incomplete in electrons ; - free radicals ; above the curie temperature the atoms are excited, the spin orientation becomes randomised, but can be realigned in an applied field and the material paramagnetic. below the curie temperature the intrinsic structure has under gone a phase transition, the atoms are ordered and the material is ferromagnetic. the paramagnetic materials induced magnetic fields are very weak in comparison to ferromagnetic materials magnetic fields. materials are only ferromagnetic below their corresponding curie temperatures. ferromagnetic materials are magnetic in the absence of an applied magnetic field. when a magnetic field is absent the material has spontaneous magnetization which is a result of the ordered magnetic moments ; that is for ferromagnetism, the atoms are symmetrical and aligned in the same direction creating a permanent magnetic field. the magnetic interactions are held together by exchange interactions ; otherwise thermal disorder would overcome the weak interactions of magnetic moments. the exchange interaction has a zero probability of parallel electrons occupying the same point in time implying a preferred parallel alignment in the material. the boltzmann factor contributes heavily as it prefers interacting particles to be aligned in the same direction. this is what causes ferromagnets to have strong magnetic fields and high curie temperature ' s around 1000k. below the curie temperature the atoms are aligned and parallel causing spontaneous magnetism ; the material is ferromagnetic. above the curie temperature the material is paramagnetic as the atoms lose their ordered magnetic moments as the material undergoes a phase transition. not to be confused with ferromagnetic. materials are only ferrimagnetic below their materials corresponding curie temperature. ferrimagnetic materials are magnetic in the absence of an applied magnetic field and are made up of two different ions. when a magnetic field is absent the material has a spontaneous magnetism which is the result of ordered magnetic moments ; that is, for ferrimagnetism one ion ' s magnetic moments are aligned facing in one direction with certain magnitude and the other ion ' s magnetic moments are aligned facing in the opposite direction with a different magnitude. as the magnetic moments are of different magnitudes in opposite directions there is still a spontaneous magnetism and a magnetic field is present. similar to ferromagnetic materials the magnetic interactions are held together by exchange interactions. the orientations of moments however are anti - parallel which results in a net momentum by subtracting their momentum from one


one. | | g | | the lande g - factor | | j ( j + 1 ) | | the eigenvalue for eigenstate j2 for the stationary states within the incomplete atoms shells ( electrons unpaired ) | | µb | | the bohr magneton | | total magnetism | | is n number of magnetic moments per unit volume | the curie - weiss law is then derived from curie ' s law to be for full derivation see curie - weiss law physics of curie temperature approaching curie temperature from above as the curie - weiss law is an approximation a more accurate model is needed when the temperature, t, approaches the materials curie temperature, tc. magnetic susceptibility occurs above the curie temperature. an accurate model of critical behaviour for magnetic susceptibility with critical exponent γ ; as temperature is inversely proportional to magnetic susceptibility when t approaches tc the denominator tends to zero and the magnetic susceptibility approaches infinity allowing magnetism to occur. this is a spontaneous magnetism which is a property of ferromagnetic and ferrimagnetic materials. approaching curie temperature from below magnetism depends on temperature and spontaneous magnetism occurs below the curie temperature. an accurate model of critical behaviour for spontaneous magnetism with critical exponent β ; the critical exponent differs between materials and for the mean - field model as taken as β = 0. 5 where t < < tc. the spontaneous magnetism approaches zero as the temperature increases towards the materials curie temperature. the spontaneous magnetism, occurring in ferromagnetic, ferrimagnetic and antiferromagnetic materials, approaches zero as the temperature increases towards the material ' s curie temperature. spontaneous magnetism is at its maximum as the temperature approaches 0k. that is, the magnetic moments are completely aligned and at their strongest magnitude of magnetism due to no thermal disturbance. in paramagnetic materials temperature is sufficient to overcome the ordered alignments. as the temperature approaches 0k the entropy decreases to zero, that is, the disorder decreases and becomes ordered. this occurs without the presence of an applied magnetic field and obeys the third law of thermodynamics. both curie ' s law and the curie - weiss law fail as the temperature approaches 0k. this is because they depend on the magnetic susceptibility which only applies when the state is disordered. gadolinium sulphate continues to satisfy


, which gives a specific size of magnetic moment to the electron ; the bohr magneton. electrons orbiting around the nucleus in a current loop create a magnetic field which depends on the bohr magneton and magnetic quantum number. therefore the magnetic moments are related between angular and orbital momentum and affect each other. angular momentum contributes twice as much to magnetic moments than orbital. for terbium which is a rare earth metal and has a high orbital angular momentum the magnetic moment is strong enough to affect the order above its bulk temperatures. it is said to have a high anisotropy on the surface, that is it ' s highly directed in one orientation. it remains ferromagnetic on its surface above its curie temperature while it ' s bulk becomes ferrimagnetic and then at higher temperatures it ' s surface remains ferrimagnetic above its bulk neel temperature before becoming completely disordered and paramagnetic with increasing temperature. the anisotropy in the bulk is different to its surface anisotropy just above these phase changes as the magnetic moments will be ordered differently or ordered in paramagnetic materials. changing a material ' s curie temperature composite materials composite materials, that is, materials composed from other materials with different properties, can change the curie temperature. for example a composite which has silver in can create spaces for oxygen molecules in bonding which decreases the curie temperature as the crystal lattice will not be as compact. the alignment of magnetic moments in the composite material affects the curie temperature. if the materials moments are parallel with each other the curie temperature will increase and if perpendicular the curie temperature will decrease as either more or less thermal energy will be needed to destroy the alignments. preparing composite materials through different temperatures can result in different final compositions which will have different curie temperatures. doping a material can also affect it ' s curie temperature. the density of nanocomposite materials changes the curie temperature. nanocomposites are compact structures on a nano - scale. the structure is built up of high and low bulk curie temperatures, however will only have one mean - field curie temperature. a higher density of lower bulk temperatures results in a lower mean - field curie temperature and a higher density of higher bulk temperature significantly increases the mean - field curie temperature. in more than one dimension the curie temperature begins to increase as the magnetic moments will need more thermal energy to overcome the ordered structure. particle size the size of particles in a material ' s crystal


temperature significantly increases the mean - field curie temperature. in more than one dimension the curie temperature begins to increase as the magnetic moments will need more thermal energy to overcome the ordered structure. particle size the size of particles in a material ' s crystal lattice changes the curie temperature. due to the small size of particles ( nanoparticles ) the fluctuations of electron spins become more prominent, this results in the curie temperature drastically decreasing when the size of particles decrease as the fluctuations cause disorder. the size of a particle also affects the anisotropy causing alignment to become less stable and thus lead to disorder in magnetic moments. the extreme of this is superparamagnetism which only occurs in small ferromagnetic particles and is where fluctuations are very influential causing magnetic moments to change direction randomly and thus create disorder. the curie temperature of nanoparticles are also affected by the crystal lattice structure, body - centred cubic ( bcc ), face - centred cubic ( fcc ) and a hexagonal structure ( hcp ) all have different curie temperatures due to magnetic moments reacting to their neighbouring electron spins. fcc and hcp have tighter structures and as a results have higher curie temperatures than bcc as the magnetic moments have stronger effects when closer together. this is known as the coordination number which is the number of nearest neighbouring particles in a structure. this indicates a lower coordination number at the surface of a material than the bulk which leads to the surface becoming less significant when the temperature is approaching the curie temperature. in smaller systems the coordination number for the surface is more significant and the magnetic moments have a stronger affect on the system. although fluctuations in particles can be minuscule, they are heavily dependent on the structure of crystal lattices as they react with their nearest neighbouring particles. fluctuations are also affected by the exchange interaction as parallel facing magnetic moments are favoured and therefore have less disturbance and disorder, therefore a tighter structure influences a stronger magnetism and therefore a higher curie temperature. pressure changes a material ' s curie temperature. increasing pressure on the crystal lattice decreases the volume of the system. pressure directly affects the kinetic energy in particles as movement increases causing the vibrations to disrupt the order of magnetic moments. this is similar to temperature as it also increases the kinetic energy of particles and destroys the order of magnetic moments and magnetism. pressure also affects the density of states ( dos ). here the dos decreases causing the number of electrons available to the system to decrease. this leads to the number of magnetic moments decreasing as they depend


and destroys the order of magnetic moments and magnetism. pressure also affects the density of states ( dos ). here the dos decreases causing the number of electrons available to the system to decrease. this leads to the number of magnetic moments decreasing as they depend on electron spins. it would be expected because of this that the curie temperature would decrease however it increases. this is the result of the exchange interaction. the exchange interaction favours the aligned parallel magnetic moments due to electrons being unable to occupy the same space in time and as this is increased due to the volume decreasing the curie temperature increases with pressure. the curie temperature is made up of a combination of dependencies on kinetic energy and the dos. it is interesting to note that the concentration of particles also affects the curie temperature when pressure is being applied and can result in a decrease in curie temperature when the concentration is above a certain percent. orbital ordering orbital ordering changes the curie temperature of a material. orbital ordering can be controlled through applied strains [ disambiguation needed ]. this is a function that determines the wave of a single electron or paired electrons inside the material. having control over the probability of where the electron will be allows the curie temperature to be altered. for example the delocalised electrons can be moved onto the same plane by applied strains within the crystal lattice. the curie temperature is seen to increase greatly due to electrons being packed together in the same plane, they are forced to align due to the exchange interaction and thus increases the strength of the magnetic moments which prevents thermal disorder at lower temperatures. curie temperature in ferroelectric and piezoelectric materials in analogy to ferromagnetic and paramagnetic materials, the curie temperature can also used to describe the temperature where a material ' s spontaneous electric polarisation changes to induced electric polarisation, or vice versa. electric polarisation is a result of aligned electric dipoles. aligned electric dipoles are composites of positive and negative charges where all the dipoles are facing in one direction. the charges are separated from their stable placement in the particles and can occur spontaneously, from pressure or an applied electric field. ferroelectric, dielectric ( paraelectric ) and piezoelectric materials have electric polarisation. in ferroelectric materials there is a spontaneous electric polarisation in the absence of an applied electric field. in dielectric materials there is electric polarisation aligned only when an electric field is applied. piezoelectric materials have electric polar


. in ferroelectric materials there is a spontaneous electric polarisation in the absence of an applied electric field. in dielectric materials there is electric polarisation aligned only when an electric field is applied. piezoelectric materials have electric polarisation due to applied mechanical stress distorting the structure from pressure. t0 is the temperature where ferroelectric materials lose their spontaneous polarisation as a first or second order phase change occurs, that is the internal structure changes or the internal symmetry changes. in certain cases t0 is equal to the curie temperature however the curie temperature can be 10 kelvin lower than t0. | below t0 | | above t0 | all ferroelectric materials are piezoelectric. an external force applies pressure on particles inside the material which affects the structure of the crystal lattice. particles in a unit cell become unsymmetrical which allows a net polarisation from each particle. symmetry would cancel the opposing charges out and there would be no net polarisation. below the transition temperature t0 displacement of electric charges causes polarisation. above the transition temperature t0 the structure is cubic and symmetric, causing the material to become dielectric. electric charges are also agitated and disordered causing the material to have no electric polarisation in the absence of an applied electric field. ferroelectric and dielectric materials are only ferroelectric below their corresponding transition temperature t0. ferroelectric materials are all piezoelectric and therefore have a spontaneous electric polarisation as the structures are unsymmetrical. materials are only dielectric above their corresponding transition temperature t0. dielectric materials have no electric polarisation in the absence of an applied electric field. the electric dipoles are unaligned and have no net polarisation. in analogy to magnetic susceptibility, electric susceptibility only occurs above t0. ferroelectric materials when polarised are influenced under hysteresis ( figure 4 ) ; that is they are dependent on their past state as well as their current state. as an electric field is applied the dipoles are forced to align and polarisation is created, when the electric field is removed polarisation remains. the hysteresis loop depends on temperature and as a result as the temperature is increased and reaches t0 the two curves become one curve as shown in the dielectric polarisation ( figure 5 ). a heat - induced ferromagnetic - paramagnetic transition is used in


as a result as the temperature is increased and reaches t0 the two curves become one curve as shown in the dielectric polarisation ( figure 5 ). a heat - induced ferromagnetic - paramagnetic transition is used in magneto - optical storage media, for erasing and writing of new data. famous examples include the sony minidisc format, as well as the now - obsolete cd - mo format. other uses include temperature control in soldering irons, and stabilizing the magnetic field of tachometer generators against temperature variation. see also - " pierre curie - biography ". nobelprize. org. the nobel foundation 1903. retrieved 14 / 03 / 2013. - buschow 2001, p5021, table 1 - jullien 1989, p. 155 - kittel 1986 - hall 1994, p. 200 - jullien 1989, pp. 136 - 138 - luth, harald ibach, hans ( 2009 ). solid - state physics : an introduction to principles of materials science ( 4th extensively updated and enlarged ed. ed. ). berlin : springer. isbn 978 - 3 - 540 - 93803 - 3. - levy 1968, pp. 236 - 239 - dekker 1958, pp. 217 - 220 - levy 1968 - fan 1987, pp. 164 - 165 - dekker 1958, pp. 454 - 455 - mendelssohn 1977, p. 162 - levy 1968, pp. 198 - 202 - cusack 1958, p. 269 - hall 1994, pp. 220 - 221 - palmer 2007 - hall 1994, p. 220 - jullien 1989, pp. 158 – 159 - jullien 1989, pp. 156 - 157 - jullien 1989, pp. 153 - hall 1994, pp. 205 - 206 - levy 1968, pp. 201 - 202 - kittel 1996, pp. 444 - myers 1997, pp. 334 - 345 - hall 1994, pp. 227 - 228 - kittel 1986, pp. 424 - 426 - spaldin 2010, pp. 52 - 54 - hall 1994, pp. 225 - mendelssohn 1977, pp. 180 - 181 - mendelssohn 1977, p. 167 - bertoldi 2012 - brout 1965, pp. 6 - 7 - jullien 1989, p. 161 - rau 1988 - skomski 2000 - jullien 1989, pp. 138 - hall 1994 - hwang 1998 - jones 2003 - lopez -


- brout 1965, pp. 6 - 7 - jullien 1989, p. 161 - rau 1988 - skomski 2000 - jullien 1989, pp. 138 - hall 1994 - hwang 1998 - jones 2003 - lopez - dominguez 2012 - bose 2011 - sadoc 2010 - myers 1997, pp. 404 - 405 - jullien 1989, pp. 56 - 59 - hall 1994, p. 275 - webster 1999 - kovetz 1990, p. 116 - pascoe 1973, pp. 186 - 187 - hummel 2001, pp. 189 - pascoe 1973, pp. 190 - 191 - webster, john g. ( 1999 ). the measurement, instrumentation, and sensors handbook ( [ online - ausg. ] ed. ). boca raton, fla. : crc press published in cooperation with ieee press. pp. 6. 55 – 6. 56. isbn 9780849383472. - pallas - areny & webster 2001, pp. 262 – 263 - buschow, k. h. j. ( 2001 ). encyclopedia of materials : science and technology. elsevier. isbn 0 - 08 - 043152 - 6. - kittel, charles ( 1986 ). introduction to solid state physics ( sixth ed. ). john wiley & sons. isbn 0 - 471 - 87474 - 4. - pallas - areny, ramon ; webster, john g ( 2001 ). sensors and signal conditioning ( 2nd ed. ). john wiley & sons. pp. 262 – 263. isbn 978 - 0 - 471 - 33232 - 9. - spaldin, nicola a. ( 2010 ). magnetic materials : fundamentals and applications ( 2nd ed. ). cambridge : cambridge university press. isbn 9780521886697. - ibach, harald ; luth, hans ( 2009 ). solid - state physics : an introduction to principles of materials science ( 4th extensively updated and enlarged ed. ). berlin : springer. isbn 9783540938033. - levy, robert a ( 1968 ). principles of solid state physics. academic press. isbn 978 - 0124457508. - fan, h. y ( 1987 ). elements of solid state physics. wiley - interscience. isbn 9780471859871. - dekker, adrianus j ( 1958 ). solid state physics. macmillan. isbn 9780333106235.


. elements of solid state physics. wiley - interscience. isbn 9780471859871. - dekker, adrianus j ( 1958 ). solid state physics. macmillan. isbn 9780333106235. - cusack, n ( 1958 ). the electrical and magnetic properties of solids. longmans, green. - hall, j. r. hook, h. e. ( 1994 ). solid state physics ( 2nd ed. ). chichester : wiley. isbn 0471928054. - jullien, andre guinier ; remi ( 1989 ). the solid state from superconductors to superalloys ( pbk. ed. ). oxford : oxford univ. press. isbn 0198555547. - mendelssohn, k. ( 1977 ). the quest for absolute zero : the meaning of low temperature physics. with s. i. units. ( 2nd ed. ). london : taylor and francis. isbn 0850661196. - myers, h. p. ( 1997 ). introductory solid state physics. ( 2nd ed. ed. ). london : taylor & francis. isbn 0748406603. - kittel, charles ( 1996 ). introduction to solid state physics ( 7. ed. ed. ). new york [ u. a. ] : wiley. isbn 0471111813. - palmer, john ( 2007 ). planar ising correlations ( [ online - ausg. ]. ed. ). boston : birkhauser. isbn 9780817646202. - bertoldi, dalia s ; bringa, eduardo m ; miranda, e n ( 6 june 2012 ). " analytical solution of the mean field ising model for finite systems ". journal of physics : condensed matter 24 ( 22 ) : 226004. doi : 10. 1088 / 0953 - 8984 / 24 / 22 / 226004. retrieved 12 / 02 / 2013. - brout, robert ( 1965 ). phase transitions. new york, amsterdam : w. a. benjamin. inc. - rau, c. ; jin, c. ; robert, m. ( 1 january 1988 ). " ferromagnetic order at tb surfaces above the bulk curie temperature ". journal of applied physics 63 ( 8 ) : 3667. doi : 10. 1063 / 1. 34067


. ( 1 january 1988 ). " ferromagnetic order at tb surfaces above the bulk curie temperature ". journal of applied physics 63 ( 8 ) : 3667. doi : 10. 1063 / 1. 340679. - skomski, r. ; sellmyer, d. j. ( 1 january 2000 ). " curie temperature of multiphase nanostructures ". journal of applied physics 87 ( 9 ) : 4756. doi : 10. 1063 / 1. 373149. - lopez - dominguez, victor ; hernandez, joan manel ; tejada, javier ; ziolo, ronald f. ( 8 january 2013 ). " colossal reduction in curie temperature due to finite - size effects in cofe o nanoparticles ". chemistry of materials 25 ( 1 ) : 6 – 11. doi : 10. 1021 / cm301927z. - bose, s. k. ; kudrnovsky, j. ; drchal, v. ; turek, i. ( 1 november 2011 ). " pressure dependence of curie temperature and resistivity in complex heusler alloys ". physical review b 84 ( 17 ). doi : 10. 1103 / physrevb. 84. 174422. - webster, john g. ( 1999 ). the measurement, instrumentation, and sensors handbook ( [ online - ausg. ] ed. ). boca raton, fla. : crc press published in cooperation with ieee press. isbn 0849383471. - kovetz, attay ( 1990 ). the principles of electromagnetic theory. ( 1st published. ed. ). cambridge [ england ] : cambridge university press. isbn 0 - 521 - 39997 - 1. - hummel, rolf e. ( 2001 ). electronic properties of materials ( 3. ed. ed. ). new york [ u. a. ] : springer. isbn 0 - 387 - 95144 - x. - pascoe, k. j. ( 1973 ). properties of materials for electrical engineers. new york, n. y. : j. wiley and sons. isbn 0471669113. - jones, paulsen, jason a. lo, chester c h ; snyder, john e. ; ring, a. p. ; jones, l. l. ; jiles, david c. ( sept. 2003 ). study


##3. - jones, paulsen, jason a. lo, chester c h ; snyder, john e. ; ring, a. p. ; jones, l. l. ; jiles, david c. ( sept. 2003 ). study of the curie temperature of cobalt ferrite based composites for stress sensor applications. 39, issue : 5. p. 3316 - 3318. - hwang, hae jin ; nagai, toru ; ohji, tatsuki ; sando, mutsuo ; toriyama, motohiro ; niihara, koichi ( 21 january 2005 ). " curie temperature anomaly in lead zirconate titanate / silver composites ". journal of the american ceramic society 81 ( 3 ) : 709 – 712. doi : 10. 1111 / j. 1151 - 2916. 1998. tb02394. x. - sadoc, aymeric ; mercey, bernard ; simon, charles ; grebille, dominique ; prellier, wilfrid ; lepetit, marie - bernadette ( 1 january 2010 ). " large increase of the curie temperature by orbital ordering control ". physical review letters 104 ( 4 ). doi : 10. 1103 / physrevlett. 104. 046804. - " pierre curie - biography ". nobelprize. org, from nobel lectures, physics 1901 - 1921, elsevier publishing company, amsterdam, 1967. the nobel foundation 1903. retrieved 14 / 03 / 2013.


exemplary embodiment of fig. 1, the junction is formed by a semiconductor region 12 of the p + type formed in an n type well 11, itself formed in a p - type of semiconductor substrate 10. the types of conductivity could furthermore be all reversed. the semiconductor may be silicon. the p + type region 12 may be demarcated laterally by thick insulating zones 14, preferably made of thick silicon oxide formed by localized thermal oxidation. the size of the region 12 may be some micrometers long by some micrometers wide. the depth of the region 12 is small : some tenths of a micrometer, preferably about 0. 2 micrometers. the concentration of n type impurities in the well is preferably the same as that used to form the wells of the p channel transistors of cmos integrated circuits. this concentration is, for example, 10. sup. 18 to 10. sup. 19 atoms per cm. sup. 3 approximately. the doping impurity may be phosphorus or arsenic, for example. the concentration of p + type impurities in the shallow region 12 is preferably the same as that used to form the self - aligned sources and drains of the p channel mos transistors. this concentration is, for example, about 10. sup. 18 to 10. sup. 20 atoms per cm. sup. 3 approximately. the doping impurity may be boron, for example. the upper part of the region 12 is in contact with a metal conductor 16 forming a first terminal a of the fuse. another metal conductor 18, electrically connected to the n - well, constitutes the other terminal b of the fuse. the conductors may be made of aluminium, for example, which is a metal commonly used in the field of silicon integrated circuits. aluminium has good properties of diffusion in silicon in the presence of a rise in temperature. this is why it is possible to make the conductor 16 out of aluminium. other metals with similar properties could also be used instead of aluminium. the conductor 18 is in contact with an n + type diffused region 20 that is locally diffused on the surface of the well and enables the setting up of an ohmic contact between the n well and the terminal b. this n + region 20 is separated from the p + region 12, for example by a portion of a thick insulator oxide region 14. the n + region 20 may surround the entire region 12. fig. 1 corresponds to an embodiment where


kaizen is a japanese word which means continuous improvement. under this model it is believed that ongoing small changes will help the organisation to continuously progress or as some commentators have said “ evolve ”. as they are small changes they can apply to all areas of the business. under kaizen theory there is no limit to continuous improvement, so the improvement process will never end. anyone and everyone under kaizen theory all employees at all levels can come up with a change. it is believed that changes suggested by the people involved in the processes ( that the changes are about ) are going to be more effective. this is because such people have first hand experience of the process, they are aware of problems and their impact ; they may even be involved in previous changes that were not effective. kaizen theory values employees and invests in them. in a kaizen environment every employee has two jobs ; their company job and their job to look for areas which could benefit from improvement and provide suggestions on how to improve. the challenge for the management team is to convince employees that they have two jobs and one is just as important as the other. teamwork and cells for a kaizen business teamwork is paramount. employees will work together to improve individual and team performance. each team is known as a cell and will be responsible for a particular area of production. each cell is believed to be experts in their area of production and will be encouraged to hold discussions ( quality circles ) about how production can be improved. a kaizen organisation will gave each idea serious consideration and decide on which ones to implement. such consideration and implementation is important, if employees ' ideas are not implemented they will lose faith in the kaizen ethos and kaizen strategy will fail. targets and “ level – up ” to encourage employees to suggest ideas, kaizen includes setting employee and cell targets. achievement against targets will be on display so that everyone in the company can see how well the cell is doing. the posters showing a cells performance against their targets is known a “ level - up ” chart


american heritage® dictionary of the english language, fourth edition - n. a person who experiences synesthesia, as by having a secondary sensation of sound as color or of color as sound. - n. alternative spelling of synaesthete. “ the protagonist is a synesthete, which is unusual enough that most readers would probably consider it a novelty. ” “ on second reading, this does seem like i ' m dumbing the term " synesthete " as i accuse others with " curate. ” “ and i also found out a while back that i ' m a synesthete. ” “ i think this has something to do with my being a synesthete? idk. ssj4gogeta wewillchange ” “ what is the significance of yllis being a synesthete? ” “ but as we passed from america to africa, i, yllis slepy, synesthete that i am, saw orange neon and digital black during a personality - free thursday in the personality - free month of september, even as i tasted and smelled and otherwise sensed what seemed an ocean of feeling in that plane. ” “ some say every person on earth is a synesthete, but that the remaining 999, 990 people out of a million experience synesthesia only on a subconscious level. ” “ what prompted the idea to have a character in the story be a synesthete? ” “ is every synesthete like me : a reflection, an absorption, a sponge? ” “ for instance : a synesthete might see colors when listening to music, or taste flavors when hearing a spoken word. ” these user - created lists contain the word ‘ synesthete ’. looking for tweets for synesthete.


| | | | | book brief | the history of modern science : a guide to the second scientific revolution, 1800 - 1950. stephen g. brush. iowa state univ. press ( 1988 ). isbn 0 - 8138 - 0883 - 9. $ 41. 95 cloth. comprehensive. brush has assembled a comprehensive guide to studying major developments in science from roughly the emergence of professional scientists ( around the turn of the 19th century ) to well into this century. during this period, the mechanistic, deterministic world view introduced by newton, descartes, boyle ( etc. ) in the " first " scientific revolution, was gradually undermined by discoveries in thermodynamics, evolutionary biology, psychology and nuclear physics. brush calls this the second scientific revolution. the volume is fashioned mostly for someone organizing a history of science course, but its contents and organization make it indispensable for the teacher serious about understanding the origins of modern scientific concepts and for reading about them more fully from high - quality sources. in fact, as the subtitle suggests, it is more a guide than an authentic history. the history is provided in brief synopses, designed to make sense of developments in a particular field or around certain key concepts. brush covers the ground very fast. these sketches are the framework for the primary emphasis : an extensive listing of specific historical sources. brush kindly addresses the non - specialist by focusing on books and periodicals that are more widely available and easily readable. also, this is a book more in essay format, useful for longer - term organizing and planning : do not expect the index to give you information and ready references to use in class the next day. the book is decidedly selective in the topics it addresses - - omitting, for example, the histories of the periodic table and of cell theory ( which are readily available elsewhere ). the main strength of the book, however, is precisely this alternative organization. brush emphasizes what gerald holton has called themata - - general concepts that permeate numerous fields : concepts such as atomism ( reduction into particulate units ), evolution ( dynamic unfolding ), randomness ( or indeterminism ), and energy ( a " kinetic worldview " ). as described and organized by brush ( see esp. the 14 - page survey in chap. 1 ), these themata form important interdisciplinary threads. for example, they help place anthropology, psychology and statistics, say, in the conventional contexts of chemistry, astronomy and pale


brush ( see esp. the 14 - page survey in chap. 1 ), these themata form important interdisciplinary threads. for example, they help place anthropology, psychology and statistics, say, in the conventional contexts of chemistry, astronomy and paleontology. departments trying to develop a program that integrates their biology, chemistry, physics and earth science classes will find many valuable clues here. the themata are also important to general history teachers, who will find the origins of significant social ideas - - say, about the origin of man and cultures ; the physical nature of the mind ; or the modern role of quantification. the chapters are organized to highlight these themes, and are worth listing here : evolution ; evolution of races and cultures ; gender and genetics ; freud and psychoanalyis ; behavior and intelligence ; atoms, energy and statistics ; electromagnetism and relativity ; atomic structure ; the explosion of physics ; and astronomy in the 19th and 20th centuries, respectively. as the chapter titles indicate, brush makes occasional excursions into several significant sub - topics, such as the history of the iq test, science and politics after the bomb, and questions of gender in science. the volume is largely an annotated outline. nevertheless, brush also comments on the ways we think about the past. he carefully exposes common prejudices about history - - and, indeed, about many scientific theories. he also devotes one chapter to philosophical and social perspectives, giving the novice a whirlwind tour of the variety of approaches now used to viewing the practice of science. | ships helps teachers share resources for integrating history, philosophy and sociology in the science classroom. e - mail us at firstname. lastname @ example. org for our quarterly news. | | |


password policy guidelines this document introduces the basic concepts of network authentication. in particular, it focuses on the use of login ids and passwords to verify the identity of users. various strategies for selecting strong, hard - to - guess passwords are then discussed. the role of passwords in authentication most shared computer systems limit access to data and resources, based on the identity of users who request that access. access control is therefore dependent on reliable user identification. authentication is the process of identifying users in a manner which makes it difficult for one user to impersonate another. a number of technologies are available for user authentication. the most popular authentication systems are : - secret passwords. - cryptographic certificates. - smart cards. - biometric devices ( fingerprints, retina scans, head scans, etc. ). since they are the least expensive to implement, most systems rely on passwords to authenticate users. as well, passwords are often used in addition to physical or cryptographic proofs of identity to further strengthen security. threats to password security a typical case involves a malicious user ( m ) trying to access a network resource for which m is not authorized. one of the easiest ways for m to access that network resource is to guess the password of a valid user ( v ). there are several methods that m could use to guess v ' s password. first, m could use a computer program to try out possible values for v ' s password very quickly. m could also acquire v ' s password by watching as v enters it. m could literally watch v typing, or could use electronic means, such as installing software on v ' s computer to record his keystrokes, or installing a network analyzer to monitor v ' s keystrokes as they are transmitted over the network. making passwords hard to guess the responsibility of selecting a password that is hard to guess generally falls to users, like v. if users choose a one - character password, and that character could be any uppercase letter, lowercase letter or digit, then there would be 62 possible passwords. clearly, m could try all 62 possibilities very quickly. v could make his / her password harder to guess by using more characters. using the same possible characters, there are 3844 possible two - character passwords, and 218340105584896 ( about 218 trillion ) 8 - character passwords. even if m could try out 5000 eight - character passwords per second, it would take, on average, 700 years for m to


of a cat to represent the newspaper. the teleological theories that are currently on offer are generally theories of referential content ( not theories of cognitive content or mode of presentation ). many philosophers would agree that referential content, which is normative in the aforementioned sense, is not narrow content. by definition, two individuals who are physical replicas at time t “ from the skin in ” must have the same narrow - content states at t. proponents of teleological theories do not believe that referential content is narrow. this view is also shared by other philosophers who think that referential content supervenes ( in part ) on things that are external to individual thinkers, such as on features of their social and physical environment and / or their history ( for the kinds of reasons raised by putnam ( 1975 ) and burge ( 1979, 1986 ) ). in general, the proponents of teleological theories of content have shown little interest in the notion of narrow content, since they tend to reject the claim that cognitive science should restrict itself to using narrow notions. still, a teleological theory of mental content could be combined with the view that cognitive science needs a narrow notion of content. a teleological theory of content tries to explain the nature of psycho - semantic norms ( i. e., semantic norms insofar as they apply to mental representations ). it is to some extent a separate question whether such norms play a role in cognitive science and whether a narrow notion is needed instead or in addition. a further point about broad aims is that teleological theories of mental content are not usually intended as theories about how we grasp meanings or are conscious of them. to grasp a meaning is plausibly a sophisticated intentional state that involves representations of meanings and not just representations with meanings. to understand how we grasp meanings, we might turn to psychological theories of concept possession and introspective access to conceptual structures. such theories presuppose that there are representations with content, whereas teleological theories of mental content try to explain the nature of intentionality at its most fundamental ; they aim to say how we can, to begin with, have any representations with content. a final point about broad aims is that teleological theories of mental content are usually intended as real nature theories. these theories do not try to describe the criteria that we use in everyday life to identify the beliefs and desires of people, the criteria used in folk psychological intentional ascriptions ( though price ( 2001 ) is an exception ). those who offer real nature


pumping blood. in the latter case, however, the selection is “ natural ” or, better, it is a non - intentional process. some who favor teleological theories of mental content claim that mother nature is intentional or purposive. in the case of millikan ( 2002 ), it is unclear whether there is a genuine as opposed to terminological disagreement with the substance of the preceding paragraph. the transition from metaphor to dead metaphor to literal use of such terms as “ design ” and “ purpose ” is a matter of degree and millikan seems to use “ function ” and “ biological purpose ” as synonyms. however, dennett ' s ( 1988 ) claim is that there is no mind - independent determinate fact of the matter about meanings or functions and that the functions of artifacts, the functions of biological systems and the contents of the thoughts of people are all dependent on interpretation, on our adopting either the design stance or the intentional stance toward them. in dennett ' s view, nature leaves functions and meanings similarly indeterminate. there are some who would prefer to reserve the term “ teleological ” for genuinely purposive contexts in the most literal sense of “ purposive ” and to refer to biological functions as “ teleonomic. ” but, on a broader construal of what it means for a concept to be teleological, a concept might be counted as teleological if it concerns what something is for, and the notion of what something was selected for counts as teleological in that sense. this is the sense of the term “ teleological ” used in this entry. intuitively, the relevant concept of function seems to be normative as well, for biologists routinely talk about systems functioning normally or properly, as well as about malfunctioning, dysfunction, functional impairment and so on. those who offer teleological theories of mental content agree that the relevant notion of function permits the possibility of malfunction ; it allows that a token trait could have a function to do z even if it lacks the disposition to do z. for example, joe ' s pineal gland could have the function to secrete melatonin even if it cannot secrete melatonin because it is malfunctioning. whether it is appropriate to describe this as “ normative ” is more controversial but the disagreement is more terminological than substantial among those offering teleological theories of mental content, since all that is usually meant by saying that the notion is


this and other theories of function could turn to several volumes of readings that have appeared : see esp. allen, bekoff & lauder ( 1998 ), buller ( 1999 ) and ariew, cummins & perlman ( 2002 ). ) it is usual to note that etiological ( teleological ) functions are distinct from the causal - role functions involved in what is usually called “ functionalism ” in philosophy of mind. causal - role functions are often defined as a select subset of a trait ' s actual causal dispositions, and functionalism is often defined as the view that mental states are individuated or classified into types on the basis of such dispositions ( see, e. g., block ( 1984 ) ). if causal - role functions are a subset of dispositions actually possessed by token traits then they do not permit the possibility of malfunction because a trait cannot have the causal - role function to z and at the same time lack the disposition to z. that said, the distinction between functionalism and what might be termed “ teleo - functionalism ” is less stark than might be thought. one reason is that formulations of classical functionalism often spoke of the characteristic or normal causal roles of mental states. sometimes this was explicitly to allow for pathology ( see, e. g., lewis 1980 ). another reason is that, although teleological functions are often said to be selected effects or effects for which traits were selected, such functions can also be described as selected dispositions or dispositions for which traits were selected. both forms of functionalism also permit multiple physical realizability of traits that perform the same functions. what all teleological ( or “ teleosemantic ” ) theories of mental content have in common is the idea that psycho - semantic norms are ultimately derivable from functional norms. beyond saying this, it is hard to give a neat definition of the group of theories that qualify. consider, for instance, some theories that are clearly intended as alternatives to teleosemantics, such as fodor ' s ( 1990b ) asymmetric dependency theory or theories that appeal to convergence under ideal epistemic conditions ( see rey 1997 for an outline ). elaboration of these theories is beyond the scope of this entry but we can note that they both seem to need a notion of normal or proper functioning. fodor ' s theory adverts to the “ intact ” perceiver and thinker. presumably this is someone whose percept